Bilirubin is the water-soluble pigment excreted in the bile. It is a yellow to orange bile pigment produced by the breakdown of Heme and reduction of biliverdin, it normally circulates in plasma and is taken up by liver cells and conjugated to form bilirubin diglucuronide. Failure of the liver cells to excrete bile, or obstruction of the bile ducts, can cause an increased amount of bilirubin in the body fluids and lead to obstructive jaundice.